1. Field of the Invention
This invention relates to the shaping of heat softenable material sheets, in a particular, to an adjustable conveyor roll for shaping hot glass sheets of varying transverse configurations.
2a. Technical Considerations
In the manufacture of tempered shape glass sheets, glass sheets are normally heated to their heat softening temperature, shaped by one of a variety of well known forming operations, and cooled to impart at least a partial temper in the glass sheet. In particular, in a roll forming operation the glass sheet is deformed by gravity to assume a transverse and/or longitudinal curvature. Transverse curvature is formed by conveying the hot glass sheet over a series of transversely curved, longitudinally spaced forming rolls at the exit end of a heating furnace. Longitudinal curvature is formed by mounting the individual forming rolls along a longitudinally extending arc.
Current automotive design requires a variety of different glass sheet shapes and curvatures. Often times, a roll forming apparatus includes transversely curved conveyor rolls with rigid shafts so that the apparatus is limited to shaping glass to a single transverse radius of curvature. It would be advantageous to have an adjustable radius conveyor roll for use in a roll forming arrangement, wherein the roll profile can be easily adjusted to correspond to the transverse shape of different curved glass sheet configurations.
2b. Patents of Interest
U.S. Pat. No. 3,064,796 to Orwin discloses a conveyor roll for supporting belts of an endless belt conveyor, in which the load carrying run of the belt has a troughed configuration. Each roller assembly includes a bowed shaft extending continuously between end supports, and a number of spaced rollers adapted to support the trough configuration of the belt. The rolls rotate about the shaft by frictional engagement between the conveyor belt and the engaging surface of the roller.
U.S. Pat. Nos. 1,530,499 to Knode; 2,820,541 to Barnish et al; 3,089,580 to Dilgard; 3,088,580 to Hughes, and 3,092,240 to Tyler et al each disclose an adjustable conveyor roll. In particular, Knode teaches a three part conveyor roll wherein the two outer end sections of the roll may be pivoted upward relative to the horizontal center section. The remaining patents each teach a continuously curved conveyor roll, wherein the transverse radius of curvature of the rolls can be varied. In each patent the roll assembly is suspended at its opposite ends by pivoting support arms and the radius of curvature of the rolls is adjusted by pivoting the support arms so as to move the opposing ends of the conveyor roll closer or further apart. In each of these patents, the conveyor rolls are free wheeling i.e., they freely rotate about a central shaft and do not include a drive assembly to directly rotate the conveyor roll.
U.S. Pat. No. 4,311,509 to Reader et al, discloses a conveyor roll comprised of a curved shaft and a plurality of cylindrically shaped glass support members mounted around the curve shaft. Each member includes a hub having a loosely fitting tongue and groove connecting arrangement and an outer collar of material that does not mar a hot glass sheet when in contact therewith. The tongue and groove arrangement interconnects the support members so that when torque is applied to one of the end hubs of the conveyor roll, he glass engaging surfaces of the collars rotate in unison, preferably at a uniform speed, to convey the curved glass sheet.
U.S. Pat. No. 4,226,608 to McKelvey discloses flexible shaping rolls comprised of relatively tightly wound coil springs mounted on pivoting end supports by stub shafts. The transverse radius of curvature of the rolls is adjusted by positively pivoting the upper portion of end supports in order to move bearing housings which support the stub shafts, inwardly or outwardly, and simultaneously vary the angularity thereof.